Which condition is an example of a chemical change?

Which condition is an example of a chemical change?

• A. Water to ice
• B. Water to steam
• C. Raindrops turning to snow
• D. Oxygen and hydrogen combining to form water

Answer: (D)

Chemical change means a new substance is formed with a different composition. When oxygen and hydrogen combine to form water, new chemical bonds are created and the resulting substance has properties different from the starting gases. The other options involve changes in the state of the same substance (water freezing to ice, water evaporating to steam, raindrops turning into snow); these are physical changes where the chemical formula remains H2O, even though the arrangement or phase changes. Energy changes can occur in both, but only the formation of water from its elements produces a new substance.

Chemical change means a new substance is formed with a different composition. When oxygen and hydrogen combine to form water, new chemical bonds are created and the resulting substance has properties different from the starting gases. The other options involve changes in the state of the same substance (water freezing to ice, water evaporating to steam, raindrops turning into snow); these are physical changes where the chemical formula remains H2O, even though the arrangement or phase changes. Energy changes can occur in both, but only the formation of water from its elements produces a new substance.